Many words are commonly used in ordinary language. Can they become trademarks? They can if they acquire special significance in reference to particular goods. For example, "apple" is a common word, but also a trademark for computers and for recordings. The word has acquired "secondary meaning" in each product category because consumers associate it with a particular brand of product.

Secondary meaning gives trademark owners protection, but does not prevent people from using the same word for other types of products or in common conversation.

The issue of secondary meaning most often comes up during infringement lawsuits or in opposition or cancellation proceedings before the Trademark Trial and Appeal Board. Trademark distinctiveness is an important concept in the law governing trademarks and service marks.